c# (WinForms-App) export DataSet to Excel

Question

I need a solution to export a dataset to an excel file without any asp code (HttpResonpsne...) but i did not find a good example to do this...

Best thanks in advance

Answer 1

I've created a class that exports a DataGridView or DataTable to an Excel file. You can probably change it a bit to make it use your DataSet instead (iterating through the DataTables in it). It also does some basic formatting which you could also extend.

To use it, simply call ExcelExport, and specify a filename and whether to open the file automatically or not after exporting. I also could have made them extension methods, but I didn't. Feel free to.

Note that Excel files can be saved as a glorified XML document and this makes use of that.

EDIT: This used to use a vanilla StreamWriter, but as pointed out, things would not be escaped correctly in many cases. Now it uses a XmlWriter, which will do the escaping for you.

The ExcelWriter class wraps an XmlWriter. I haven't bothered, but you might want to do a bit more error checking to make sure you can't write cell data before starting a row, and such. The code is below.

public class ExcelWriter : IDisposable {     private XmlWriter _writer;      public enum CellStyle { General, Number, Currency, DateTime, ShortDate };      public void WriteStartDocument()     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteProcessingInstruction("mso-application", "progid=\"Excel.Sheet\"");         _writer.WriteStartElement("ss", "Workbook", "urn:schemas-microsoft-com:office:spreadsheet");          WriteExcelStyles();    }      public void WriteEndDocument()     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteEndElement();     }      private void WriteExcelStyleElement(CellStyle style)     {         _writer.WriteStartElement("Style", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteAttributeString("ID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());         _writer.WriteEndElement();     }      private void WriteExcelStyleElement(CellStyle style, string NumberFormat)     {         _writer.WriteStartElement("Style", "urn:schemas-microsoft-com:office:spreadsheet");          _writer.WriteAttributeString("ID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());         _writer.WriteStartElement("NumberFormat", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteAttributeString("Format", "urn:schemas-microsoft-com:office:spreadsheet", NumberFormat);         _writer.WriteEndElement();          _writer.WriteEndElement();      }      private void WriteExcelStyles()     {         _writer.WriteStartElement("Styles", "urn:schemas-microsoft-com:office:spreadsheet");          WriteExcelStyleElement(CellStyle.General);         WriteExcelStyleElement(CellStyle.Number, "General Number");         WriteExcelStyleElement(CellStyle.DateTime, "General Date");         WriteExcelStyleElement(CellStyle.Currency, "Currency");         WriteExcelStyleElement(CellStyle.ShortDate, "Short Date");          _writer.WriteEndElement();     }      public void WriteStartWorksheet(string name)     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteStartElement("Worksheet", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteAttributeString("Name", "urn:schemas-microsoft-com:office:spreadsheet", name);         _writer.WriteStartElement("Table", "urn:schemas-microsoft-com:office:spreadsheet");     }      public void WriteEndWorksheet()     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteEndElement();         _writer.WriteEndElement();     }      public ExcelWriter(string outputFileName)     {         XmlWriterSettings settings = new XmlWriterSettings();         settings.Indent = true;         _writer = XmlWriter.Create(outputFileName, settings);     }      public void Close()     {         if (_writer == null) throw new InvalidOperationException("Already closed.");          _writer.Close();         _writer = null;     }      public void WriteExcelColumnDefinition(int columnWidth)     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteStartElement("Column", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteStartAttribute("Width", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteValue(columnWidth);         _writer.WriteEndAttribute();         _writer.WriteEndElement();     }      public void WriteExcelUnstyledCell(string value)     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteStartElement("Cell", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteStartElement("Data", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "String");         _writer.WriteValue(value);         _writer.WriteEndElement();         _writer.WriteEndElement();     }      public void WriteStartRow()     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteStartElement("Row", "urn:schemas-microsoft-com:office:spreadsheet");     }      public void WriteEndRow()     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteEndElement();     }      public void WriteExcelStyledCell(object value, CellStyle style)     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          _writer.WriteStartElement("Cell", "urn:schemas-microsoft-com:office:spreadsheet");         _writer.WriteAttributeString("StyleID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());         _writer.WriteStartElement("Data", "urn:schemas-microsoft-com:office:spreadsheet");         switch (style)         {             case CellStyle.General:                 _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "String");                 break;             case CellStyle.Number:             case CellStyle.Currency:                 _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "Number");                 break;             case CellStyle.ShortDate:             case CellStyle.DateTime:                 _writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "DateTime");                 break;         }         _writer.WriteValue(value);         //  tag += String.Format("{1}\"><ss:Data ss:Type=\"DateTime\">{0:yyyy\\-MM\\-dd\\THH\\:mm\\:ss\\.fff}</ss:Data>", value,          _writer.WriteEndElement();         _writer.WriteEndElement();     }      public void WriteExcelAutoStyledCell(object value)     {         if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");          //write the <ss:Cell> and <ss:Data> tags for something         if (value is Int16 || value is Int32 || value is Int64 || value is SByte ||             value is UInt16 || value is UInt32 || value is UInt64 || value is Byte)         {             WriteExcelStyledCell(value, CellStyle.Number);         }         else if (value is Single || value is Double || value is Decimal) //we'll assume it's a currency         {             WriteExcelStyledCell(value, CellStyle.Currency);         }         else if (value is DateTime)         {             //check if there's no time information and use the appropriate style             WriteExcelStyledCell(value, ((DateTime)value).TimeOfDay.CompareTo(new TimeSpan(0, 0, 0, 0, 0)) == 0 ? CellStyle.ShortDate : CellStyle.DateTime);         }         else         {             WriteExcelStyledCell(value, CellStyle.General);         }     }      #region IDisposable Members      public void Dispose()     {         if (_writer == null)             return;          _writer.Close();         _writer = null;     }      #endregion } 

Then you can export your DataTable using the following:

public static void ExcelExport(DataTable data, String fileName, bool openAfter) {     //export a DataTable to Excel     DialogResult retry = DialogResult.Retry;      while (retry == DialogResult.Retry)     {         try         {             using (ExcelWriter writer = new ExcelWriter(fileName))             {                 writer.WriteStartDocument();                  // Write the worksheet contents                 writer.WriteStartWorksheet("Sheet1");                  //Write header row                 writer.WriteStartRow();                 foreach (DataColumn col in data.Columns)                     writer.WriteExcelUnstyledCell(col.Caption);                 writer.WriteEndRow();                  //write data                 foreach (DataRow row in data.Rows)                 {                     writer.WriteStartRow();                     foreach (object o in row.ItemArray)                     {                         writer.WriteExcelAutoStyledCell(o);                     }                     writer.WriteEndRow();                 }                  // Close up the document                 writer.WriteEndWorksheet();                 writer.WriteEndDocument();                 writer.Close();                 if (openAfter)                     OpenFile(fileName);                 retry = DialogResult.Cancel;             }         }         catch (Exception myException)         {             retry = MessageBox.Show(myException.Message, "Excel Export", MessageBoxButtons.RetryCancel, MessageBoxIcon.Asterisk);         }     } } 

Answer 2

The following site demonstrates how to export a DataSet (or DataTable or List<>) into a "genuine" Excel 2007 .xlsx file.

It uses the OpenXML libraries, so you don't need to have Excel installed on your server.

C# ExportToExcel library

All of the source code is provided, free of charge, along with instructions using it with ASP.NET, ASP.NET Core 2+ or regular C#.

It's very easy to add to your own applications, you just need to call one function, passing in an Excel filename, and your data source:

DataSet ds = CreateSampleData(); string excelFilename = "C:\\Sample.xlsx"; CreateExcelFile.CreateExcelDocument(ds, excelFilename); 

Hope this helps.